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Biomechanical Analysis of a novel aerobic training instrument

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									      Biomechanical Analysis of a novel aerobic training instrument

Introduction
As we enter a new fitness era, new products are being developed for the aerobic
enthusiasts. The Fit-ZoneTM is an athletic training program designed to improve
motor skills, reactive training, aerobic conditioning, muscular strength and
endurance, flexibility and body composition. The program involves moving inside
a square frame, with the option of performing upper torso body conditioning
movements, dependent on ability and fitness level of participants. Similar aerobic
training principles are already in use, with the most notable example being the
Reebok Step. The Fit-Zone aims to provide an effective alternative to the Reebok
Step as cardiovascular analysis has shown (Agouris & Law, 2007). Three-
dimensional Motion Analysis has been gaining popularity as an objective tool for
movement measurements. Therefore it is widely used to assess the
biomechanical effects of exercise by comparing the person’s data with healthy
population data, by comparing biomechanical parameters before and after a
therapeutic intervention or an exercise regime, or by comparing effects of
different regimes onto the same person or group of persons (Kadaba et al. 1990).

Aim and Objectives
The aim of this study was to assess the effects of exercising with the Fit-Zone,
the Reebok Step, and just the floor, using Biomechanical Analysis and
Physiological Measurements. The main objectives were:
1. To compare the calories burned during 10 minutes exercise using the Fit-
    Zone, the Reebok Step and just the floor, using a heart rate monitor.
2. To analyse and compare the stresses on the hip, knee and ankle joints during
    the same exercises, using biomechanical analysis.

Methodology
Biomechanical data was collected in the Robert Gordon University Human
Performance Laboratory. The lab was equipped with a 7-camera Vicon MX 3-D
motion analysis system (Vicon Motion Systems Ltd, Oxford) with two Kistler
piezoelectric force platforms (Kistler, Hampshire, UK). The system recorded
kinematics and kinetics of lower limb, pelvic and trunk motion. The volunteers
performed 3 movements; lateral movements in the frontal plane running
periodically on the balls of feet (movement 1), linear sagital plane movements
forward lunging (movement2) and transverse movements imitating catching and
throwing a ball (movement 3). Physiological data was collected in a private
sports centre in Aberdeen. Volunteers carried out 10 minutes of exercise activity
after a 5 minute warm up and using the same variables (speed, choreography,
polar team heart rate monitors and workout environment). The 31 volunteers
were males and females, aged 24-68, existing members of a gym and used to
exercising for up to 30-60 minutes of continuous activity. Measurements of heart
rate and energy expenditure were carried out using The Polar Teamsystem
monitor (Polar Electro UK Ltd, Warwick). Energy expenditure was calculated from
the ratio of oxygen uptake to walking velocity and expressed in millilitres of
oxygen per kilogram body weight per meter travelled. Non-parametric statistical
analysis of the biomechanics and heart rate results was carried out using
Wilcoxon test at 95% significance level.

Results
Figures 1, 2 and 3 show the internal forces on the hip, knee and ankle joints
produced by the 3 movements. The red solid line represents the Floor (no
equipment) option, the red dotted line represents the Reebok Step option and the
blue dotted line represents the Fit Zone option.
       -0




               (L,R)HipForce(Z)                  (L,R)KneeForce(Z)               (L,R)AnkleForce(Z)
       6                                   2                              10




            (R,L)NormalisedGRF(Z)*
     269




       N                                   N                              N




       N




      -22                              -22                                -5


Figure 3: Moving sideways (frontal plane): There was no significant difference in the internal forces
exerted on the hip and knee joints (p>0.05). However, the Reebok Step was found to cause
                                                                        (p=0.003) and the Floor
significantly higher stress on the ankle joint compared to the Fit Zone12
  -0
  11
              (L,R)HipPower
                                      8
                                                 (L,R)KneePower                 (L,R)AnklePower

(p=0.002) options.

               (R,L)HipForce(Z)*                (R,L)KneeForce(Z)*             (R,L)AnkleForce(Z)*
       6                               2                             10




       W    RNormalisedGRF(Z)              W                              W
269




       N                               N                             N




      -40                                  -8                         -12
 N




      -22                            -22                             -3


Figure 2: Moving forwards (linear/sagittal plane): There was no significant difference in the internal
forces exerted on all joints between the Fit Zone and the Reebok Step (p>0.05). However, the Floor
             (R,L)HipPower*                   (R,L)KneePower*                  (R,L)AnklePower*
(no equipment) was found to cause 8significantly lower stress on the ankle joint compared to the Fit
 -0 11                                                               12

Zone (p=0.02) and the Reebok Step (p=0.004) options.

               RHipForce(Z)                      RKneeForce(Z)                    RAnkleForce(Z)
 6                                    2                               10



       W                              W                              W




 N                                    N                               N



      -40                             -8                             -9




-22                                  -22                              -5



Figure 1: Transverse movement: There was no significant difference in the internal forces exerted
on the hip and knee joints (p>0.05). However, the Reebok Step was found to cause significantly
             RHipPower                        RKneePower                        RAnklePower
higher stress on the ankle joint compared to the Fit Zone (p=0.006) and the Floor (p=0.002)
11                                  8                               12

options.




 W                                    W                               W
Table 1 shows the calories burned and the percentage of heart rate increase after
each program. Wilcoxon test showed that there was no significant difference
between the calories burnt and the heart rate increase after 10 minutes of
activity with the Fit Zone (FZ) and the Reebok Step (p>0.05). However,
exercising with no equipment (floor) produced significantly lower number of
calories burnt (p=0.02) and heart rate increase (p=0.03).


Table 1: Average and standard deviation of calories burnt and increase of Heart
Rate

               Description                   FZ Height 2     Step         Floor
Overall Calories Burned                         77±9         75±8         70±7
Avg % HR increase for duration of activity    85%±11%      85%±12%      81%±10%




Discussion – Conclusions

Biomechanical Analysis showed that all three options cause similar internal stress
on the hip and knee joints. However, significant differences were found on the
ankle joint. The Reebok Step caused significantly more stress on the ankle joint
compared to the Fit Zone and the Floor options in all three exercises.

The heart rate study showed that both the Fit Zone and the Reebok Step are
more effective options in burning calories and increasing heart rate during 10
minutes of exercising.

By summarising the findings of the Biomechanical and Heart Rate Analyses, the
conclusion of this study is that the Fit Zone was a more effective alternative to
exercising with no equipment or with the Reebok Step, by increasing the number
of calories burnt without causing excessive joint stress.

The findings of this study do not consist of a general biomechanical assessment of
the tested equipment, as only three exercises were used. A further study could
include a larger number of exercises, and also electromyography analysis (EMG),
which could identify the muscle groups activated during particular exercises.


References

Agouris, I.; Law, E.J., 2007. Physiological Analysis of a novel aerobic training
instrument. Research project report, The Robert Gordon University, School of
Health Sciences.

Kadaba, M.P.; Ramakrishnan, H.K. and Wootten, M.E., 1990. Measurement of
lower extremity kinematics during level walking. Journal of Orthopaedic Research,
8 (3), pp.383-92.

								
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